Gastrointestinal specific anxiety in irritable bowel syndrome: validation of the Japanese version of the visceral sensitivity index for university students

OBJECTIVE

The visceral sensitivity index (VSI) is a useful self-report measure of the gastrointestinal symptom-specific anxiety (GSA) of patients with irritable bowel syndrome (IBS). Previous research has shown that worsening GSA in IBS patients is related to the severity of GI symptoms, suggesting that GSA is an important endpoint for intervention. However, there is currently no Japanese version of the VSI. We therefore translated the VSI into Japanese (VSI-J) and verified its reliability and validity.

MATERIAL AND METHODS

Participants were 349 university students aged 18 and 19 years and recruited from an academic class. We analyzed data from the VSI-J, Anxiety Sensitivity Index (ASI), Hospital Anxiety and Depression scale (HAD), and Irritable Bowel Syndrome Severity Index (IBS-SI). The internal consistency, stability, and factor structure of the VSI-J and its associations with anxiety, depression and severity measures were investigated.

RESULTS

The factor structure of the VSI-J is unidimensional and similar to that of the original VSI (Cronbach's α = 0.93). Construct validity was demonstrated by significant correlations with ASI (r = 0.43, p < 0.0001), HAD-ANX (r = 0.19, p = 0.0003), and IBS-SI scores (r = 0.45, p < 0.0001). Furthermore, the VSI-J was a significant predictor of severity scores on the IBS-SI and demonstrated good discriminant (p < 0.0001) and incremental (p < 0.0001) validity.

CONCLUSION

These findings suggest that the VSI-J is a reliable and valid measure of visceral sensitivity.

Operation status of the electron cyclotron resonance ion source at Gunma University

An ECR ion source of Gunma University Heavy Ion Medical Center, so-called KeiGM [M. Muramatsu, A. Kitagawa, Y. Sakamoto, S. Sato, Y. Sato, H. Ogawa, S. Yamada, H. Ogawa, Y. Yoshida, and A. G. Drentje, Rev. Sci. Instrum. 76, 113304 (2005)], has been operated for cancer therapy and physical/biological experiment since 2010. KeiGM produces typically 230 μA of 10 keV/u C(4+) ions from CH4 gases. The vacuum pressure is kept between 1.2 × 10(-4) and 1.7 × 10(-4) Pa so as to suppress the pulse-to-pulse current fluctuation within ±10%. The extraction electrode is cleaned every 6-8 months in order to remove deposited carbon, which increases the leak current and discharge. In order to investigate the possibility of long-term operation without such maintenances, oxygen aging for the cleaning of the extraction electrode has been tested in the test bench. The same-designed ion sources at National Institute of Radiological Sciences and SAGA Heavy Ion Medical Accelerator in Tosu (SAGA-HIMAT) are also operated with stable C(4+) current, which are suitable for the continuous operation for cancer therapy.

Relationship between infectious gastroenteritis and irritable bowel syndrome

A newly recognized causative factor in a subset of patients with irritable bowel syndrome (IBS) is called post-infectious IBS (PI-IBS). IBS symptoms frequently develop after an acute episode of infectious gastroenteritis. Several studies have been made in our understanding of the concept of PI-IBS. Recent studies suggest that transient or chronic gastrointestinal inflammation may play a role in IBS pathogenesis. PI-IBS can be regarded as a natural experiment model in which an insult in the form of an infective disease impacts on subjects with underlying genetic and psychosocial predispositions who then develop IBS. IBS is likely to be a complex trait wherein variability in clinical presentation is partially explained by heterogeneity in underlying genetic and environmental risk factors for PI-IBS. Further studies on PI-IBS are needed to understand the pathophysiology of functional gastrointestinal disorders and to develop new promising management for such patients.

Effects of preceding stimulation on brain activation in response to colonic distention in humans

OBJECTIVE

It has been suggested that the pattern of distension (moderate following mild and vice versa) might influence brain activation and the experience of hypersensitivity, offset analgesia, and anticipation. Nevertheless, how the pattern of stimulation affects sensitization and/or desensitization to visceral stimulation remains unknown.

METHODS

In 45 nonclinical healthy participants (12 women, 33 men; 20-26 years old), brain processing of visceral sensation induced by colonic distension was examined using H2(15)O positron emission tomography. Subjective feelings regarding the stimuli were also measured. The descending colon was stimulated using six patterns of three bag pressures (0, 20, and 40 mm Hg). To evaluate the neural sensitization to visceral stimulation arising from the precedence effect, the effects of a 20- or 40-mm Hg distention after a sham or 20- or 40-mm Hg distension were analyzed using statistical parametric mapping. The level of significance was set at a voxelwise level of p < .0001, with cluster extent sizes of k > 50.

RESULTS

The midbrain, insula, and cerebellum, were more strongly activated by a 20-mm Hg distension with a preceding 40-mm Hg distention than by a 20-mm Hg distention without a preceding stimulation (p < .0001). Conversely, a sham stimulation after the experience of an intense stimulation activated the midcingulate cortex, compared with a sham stimulation without the experience of actual visceral stimulation (p < .0001).

CONCLUSIONS

By directly comparing different patterns of visceral stimuli, preceding visceral stimuli may affect neural sensitization and/or desensitization in humans, including elevated midbrain, insula, and midcingulate cortex.

Altered cognitive function of prefrontal cortex during error feedback in patients with irritable bowel syndrome, based on FMRI and dynamic causal modeling

BACKGROUND & AIMS

Patients with irritable bowel syndrome (IBS) have increased activity in the insula and reduced activation of the dorsolateral prefrontal cortex (DLPFC) in response to visceral stimulation. We investigated whether they have latent impairments in cognitive flexibility because of dysfunction in the DLPFC and insula and altered connectivity between brain regions.

METHODS

We analyzed data from 30 individuals with IBS (15 men; age, 21.7 ± 3.0 y) diagnosed based on Rome III criteria, along with 30 individuals matched for age, sex, and education level (controls). Event-related functional magnetic resonance imaging of the brain was performed to evaluate cognitive flexibility and was assessed by the Wisconsin Card Sorting Test, in which subjects are allowed to change choice criteria, defined as set-shifting in response to error feedback. Brain images were analyzed with statistical parametric mapping 5 and 8 software and dynamic causal modeling.

RESULTS

Subjects with IBS had significantly more Nelson perseverative errors (P < .05) and set-maintenance difficulties (P < .05) than controls. They also showed significantly decreased activity of the right DLPFC (Brodmann's area 9; P < .001) and right hippocampus (P < .001), and significantly increased activity of the left posterior insula (P < .001) at error feedback during set-shifting. Dynamic causal modeling analysis during set-shifting revealed significantly less connectivity from the DLPFC to pre-supplementary motor area in subjects with IBS, compared with controls (P = .012).

CONCLUSIONS

Individuals with IBS have latent impairments in cognitive flexibility as a result of altered activity of the DLPFC, insula, and hippocampus, and impaired connectivity between the DLPFC and pre-supplementary motor area.

Corticotropin-releasing hormone receptor 1 gene variants in irritable bowel syndrome

BACKGROUND

Corticotropin-releasing hormone (CRH) acts mainly via the CRH receptor 1 (CRH-R1) and plays a crucial role in the stress-induced pathophysiology of irritable bowel syndrome (IBS). Several studies have demonstrated that variants of the CRH-R1 gene carry a potential risk for depression, but evidence for an association between CRH-R1 genotypes and IBS is lacking. We tested the hypothesis that genetic polymorphisms and haplotypes of CRH-R1 moderate the IBS phenotype and negative emotion in IBS patients.

METHODS

A total of 103 patients with IBS and 142 healthy controls participated in the study. Three single-nucleotide polymorphisms of the CRH-R1 gene (rs7209436, rs242924, and rs110402) were genotyped. Subjects' emotional states were evaluated using the Perceived-Stress Scale, the State-Trait Anxiety Inventory, and the Self-rating Depression Scale.

RESULTS

The TT genotype of rs7209436 (P = 0.01) and rs242924 (P = 0.02) was significantly more common in patients with IBS than in controls. Total sample analysis showed significant association between bowel pattern (normal, diarrhea, constipation, or mixed symptoms) and the T allele of rs7209436 (P = 0.008), T allele of rs242924 (P = 0.019), A allele of rs110402 (P = 0.047), and TAT haplocopies (P = 0.048). Negative emotion was not associated with the examined CRH-R1 SNPs.

CONCLUSION

These findings suggest that genetic polymorphisms and the CRH-R1 haplotypes moderate IBS and related bowel patterns. There was no clear association between CRH-R1 genotypes and negative emotion accompanying IBS. Further studies on the CRH system are therefore warranted.

Association between self-assessment of complete dentures and oral health-related quality of life

The purpose of this study was to determine which factors related to patient self-assessment of dentures are associated with changes in oral health-related quality of life (OHRQoL) among edentulous patients after replacement of complete dentures, and to determine whether masticatory performance as determined using an objective method affects the changes in OHRQoL among edentulous patients. As a preliminary study, the existing questionnaire regarding self-assessment of dentures consisting of 39 question items, measured with a 100-mm visual analogue scale, was analysed by factor analysis. Then a questionnaire, composed of 22 question items, was developed containing six subscales of 'function', 'lower denture', 'upper denture', 'expectation', 'aesthetic and speech' and 'importance'. Final participants in the present study comprised 93 edentulous patients requiring new conventional complete dentures (44 men, 49 women; mean age, 75·0 years). These patients were asked to complete the Japanese version of the Oral Health Impact Profile (OHIP)-EDENT, comprising 19 question items for assessment of OHRQoL in edentulous patients, along with the developed questionnaire regarding self-assessment of dentures. Moreover, masticatory performance was measured using a colour-changeable chewing gum. The questionnaire and measurement were completed twice; before and after replacement of complete dentures. Stepwise multiple regression analysis identified 'lower denture' and 'aesthetic and speech' as significant independent variables besides OHIP-EDENT scores before replacement. These results suggest that sufficient retention of lower dentures and appropriate appearance may lead to improved OHRQoL in edentulous patients.

Serotonin transporter gene promoter polymorphism and alexithymia

BACKGROUND

Recent neurobiological studies have reported that alexithymia may result from altered brain function related to emotional processing. Serotonin (5-hydroxytryptamine, 5-HT) has been shown to regulate central nervous system development associated with psychological processing. We investigated the possibility that polymorphism of the 5-HT transporter-linked promoter region (5-HTTLPR) is associated with alexithymia.

METHODS

This study included 304 healthy Japanese volunteers (148 males, 156 females). The subjects were categorized according to genotype (L/L, L/S, S/S) and results of the 20-item Toronto Alexithymia Scale (TAS-20), State-Trait Anxiety Inventory (STAI) and Self-Rating Depression Scale (SDS).

RESULTS

Subjects with the L/L genotype showed significantly higher TAS-20 scores, as well as significantly higher scores on the difficulty identifying feeling (DIF) subscale, than those with the L/S or S/S genotype (p < 0.05). There was a gender difference in the association between 5-HTTLPR genotype and DIF score. Female subjects with the L/L genotype showed significantly higher DIF scores than those with the L/S or S/S genotype (p ≤ 0.001). Neither STAI nor SDS was significantly associated with the 5-HTTLPR genotype.

CONCLUSION

These results suggest a link between low synaptic 5-HT and alexithymia.

Lifestyle and psychological factors related to irritable bowel syndrome in nursing and medical school students

BACKGROUND

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder comprising abdominal pain, abdominal discomfort, and disordered defecation. The prevalence of IBS is 10-15% in the general population. This study investigated the prevalence of IBS and the relationship between IBS and stress, lifestyle, and dietary habits among nursing and medical school students.

METHODS

A blank self-administrated questionnaire was used to survey 2,639 students studying nursing or medicine. This questionnaire asked about IBS symptoms, lifestyle, dietary intake, life events, anxiety, and depression. The questionnaires were collected from 2,365 students (89.6%) and the responses of 1,768 students (74.8%) were analyzed.

RESULTS

The prevalence of IBS was 35.5% as a whole, 25.2% in males and 41.5% in females. Significantly higher stress scores (anxiety and depression) and life events were found in the IBS group than in the non-IBS group. Sleep disorders and the time spent sitting were also higher in males with IBS. In the IBS group, females ate less fish, fruit, milk, and green-yellow vegetables, and more processed food products than the non-IBS group (p = 0.001, p = 0.002, p = 0.032, p = 0.037, p < 0.001). The rates of missed meals and irregular mealtimes were significantly higher in females in the IBS group (p = 0.001, p = 0.013).

CONCLUSIONS

The prevalence of IBS was higher among nursing and medical students, and further interventional studies are needed to improve IBS symptoms.

Effect of repetitive transcranial magnetic stimulation on rectal function and emotion in humans

BACKGROUND

A previous brain imaging study demonstrated activation of the right dorsolateral prefrontal cortex (DLPFC) during visceral nociception, and this activation was associated with anxiety. We hypothesized that functional modulation of the right DLPFC by repetitive transcranial magnetic stimulation (rTMS) can reveal the actual role of right DLPFC in brain-gut interactions in humans.

METHODS

Subjects were 11 healthy males aged 23.5 ± 1.4 (mean ± SE) years. Viscerosensory evoked potential (VEP) with sham (0 mA) or actual (30 mA) electrical stimulation (ES) of the rectum was taken after sham, low frequency rTMS at 0.1 Hz, and high frequency rTMS at 10 Hz to the right DLPFC. Rectal tone was measured with a rectal barostat. Visceral perception and emotion were analyzed using an ordinate scale, rectal barostat, and VEP.

KEY RESULTS

Low frequency rTMS significantly reduced anxiety evoked by ES at 30 mA (p < 0.05). High frequency rTMS-30 mA ES significantly produced more phasic volume events than sham rTMS-30 mA ES (p < 0.05).

CONCLUSIONS AND INFERENCES

We successfully modulated the gastrointestinal function of healthy individuals through rTMS to the right DLPFC. Thus, rTMS to the DLPFC appears to modulate the affective, but not direct, component of visceral perception and motility of the rectum.

Effect of 5-HT4 receptor agonist mosapride citrate on rectosigmoid sensorimotor function in patients with irritable bowel syndrome

BACKGROUND

The 5-HT(4) receptor agonist, mosapride citrate, accelerates gastric emptying. However, the effect of mosapride on colonic function has not been well investigated. We examined whether mosapride changes rectosigmoid motility and perception in patients with irritable bowel syndrome (IBS).

METHODS

Thirty-seven patients with IBS and 18 healthy subjects were studied. All subjects underwent a rectosigmoid barostat test to measure pain perception to intraluminal distention and resting smooth muscle motility for 20 min in the fasting state. Irritable bowel syndrome patients were then randomly assigned to receive either mosapride 15 mg (n=19) or placebo (n=18) orally with 200 mL water. Rectosigmoid motility and perception were measured again for 60 min following dosing. Rectosigmoid tone and contractility were evaluated in each 10-min period.

KEY RESULTS

The pain threshold in the patients was significantly lower than that in controls (P<0.01). There were no differences between mosapride and placebo groups in pain threshold, barostat bag volume, or number of contractions at baseline. Mosapride significantly decreased the mean bag volume (P<0.01; group × period interaction by two-way anova) and increased the mean number of contractions (P<0.05) compared with placebo, but did not affect the perception. In IBS patients with constipation (i.e., excluding diarrhea-predominant subjects), mosapride (n=13) increased rectosigmoid tone (P<0.01) and contractions (P<0.05) more than placebo (n=14).

CONCLUSIONS & INFERENCES

Mosapride stimulates colonic motility without any adverse effect. These findings suggest that mosapride may have the potential to treat IBS patients with constipation and/or functional constipation. Further clinical trials are warranted to confirm the efficacy of this agent.

Biopsychosocial model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common chronic disorder seen in gastroenterology and primary care practice. It is characterized by recurrent abdominal pain or discomfort associated with disturbed bowel function. It is a heterogeneous disorder with varying treatments, and in this regard physicians sometimes struggle with finding the optimal approach to management of patients with IBS. This disorder induces high health care costs and variably reduces health-related quality of life. IBS is in the class of functional gastrointestinal disorders, and results from dysregulation of central and enteric nervous system interactions. Psychosocial factors are closely related to their gut physiology, associated cognitions, symptom manifestations and illness behavior. Therefore, it is important for the physician to recognize the psychosocial issues of patients with IBS and in addition to build a good patient-physician relationship in order to optimize treatment. This review focuses on the interaction between psychological and physiological factors associated with IBS by using a biopsychosocial model. In this article, we describe (1) the predisposing psychological features seen in early life; (2) the psychological factors associated with life stress, the symptom presentation, and their associated coping patterns; (3) gut pathophysiology with emphasis on disturbances in motility, visceral hypersensitivity and brain-gut interactions; and finally (4) the clinical outcomes and effective treatments including psychotherapeutic methods.

Biopsychosocial model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common chronic disorder seen in gastroenterology and primary care practice. It is characterized by recurrent abdominal pain or discomfort associated with disturbed bowel function. It is a heterogeneous disorder with varying treatments, and in this regard physicians sometimes struggle with finding the optimal approach to management of patients with IBS. This disorder induces high health care costs and variably reduces health-related quality of life. IBS is in the class of functional gastrointestinal disorders, and results from dysregulation of central and enteric nervous system interactions. Psychosocial factors are closely related to their gut physiology, associated cognitions, symptom manifestations and illness behavior. Therefore, it is important for the physician to recognize the psychosocial issues of patients with IBS and in addition to build a good patient-physician relationship in order to optimize treatment. This review focuses on the interaction between psychological and physiological factors associated with IBS by using a biopsychosocial model. In this article, we describe (1) the predisposing psychological features seen in early life; (2) the psychological factors associated with life stress, the symptom presentation, and their associated coping patterns; (3) gut pathophysiology with emphasis on disturbances in motility, visceral hypersensitivity and brain-gut interactions; and finally (4) the clinical outcomes and effective treatments including psychotherapeutic methods.

Gene, environment, and brain-gut interactions in irritable bowel syndrome

The genetic predisposition and influence of environment may underlie in the pathogenesis and/or pathophysiology of irritable bowel syndrome (IBS). This phenomenon, gene x environment interaction together with brain-gut interactions is emerging area to be clarified in IBS research. Earlier studies focused on candidate genes of neurotransmitters, cytokines, and growth factors. Among them, some studies but not all studies revealed association between phenotypes of IBS and 5-hydroxytryptamine (5-HT)-related genes, noradrenaline-related genes, and cytokine genes. Recent prospective cohort study showed that genes encoding immune and adhesion molecules were associated with post-infectious etiology of IBS. Psychosocial stressors and intraluminal factors especially microbiota are keys to develop IBS. IBS patients may have abnormal gut microbiota as well as increased organic acids. IBS is disorder that relates to brain-gut interactions, emotional dysregulation, and illness behaviors. Brain imaging with or without combination of visceral stimulation enables us to depict the detailed information of brain-gut interactions. In IBS patients, thalamus, insula, anterior cingulate cortex, amygdala, and brainstem were more activated in response to visceral stimulation than controls. Corticotropin-releasing hormone and 5-HT are the candidate substances which regulate exaggerated brain-gut response. In conclusion, gene x environment interaction together with brain-gut interactions may play crucial roles in IBS development. Further fundamental research on this issue is warranted.

Effect of rikkunshito on gastric sensorimotor function under distention

BACKGROUND

The herbal medicine rikkunshito is effective for the treatment of gastrointestinal symptoms in patients with functional dyspepsia. Although some basic studies on the effects of rikkunshito have been reported in rats, its effects on human gastric function have not yet been clarified. Psychosocial stress induces visceral hypersensitivity and elements of rikkunshito may reasonably affect or suppress this process. We conducted a study to verify the hypothesis that rikkunshito improves stress-induced gastric hypersensitivity and/or changes in gastric wall tone.

METHODS

Nine healthy volunteers (five males, four females) participated in the study. The counterbalanced regimen consisted of a 2-week period of oral administration of 7.5 g day(-1) rikkunshito, then a 2-week period without treatment. Fundic sensorimotor function was examined using a gastric barostat twice on the day after each period. Virtual reality stress was imposed during the measurements of gastric tone and electrocardiogram.

KEY RESULTS

Stress induced a significant increase in heart rate (P = 0.041), gastric volume (P = 0.008), and phasic volume events (P = 0.049) and a decrease in sensory (P = 0.038), discomfort (P = 0.011), and pain (P = 0.041) thresholds of the stomach. Rikkunshito significantly reduced epigastric fullness (P = 0.037) and perceived stress (P = 0.034) following stimulation of the pain threshold, regardless of stress without the drug. Stress reduced gastric volume at the sensory threshold and increased anxiety at the discomfort threshold, and these responses were significantly inhibited by rikkunshito (P = 0.026, P = 0.022, respectively).

CONCLUSIONS & INFERENCES

These findings suggest that rikkunshito may improve symptoms and impaired gastric accommodation under distention stimuli of the proximal stomach superimposed by stress.

Visceral hypersensitivity in irritable bowel syndrome

Altered central processing, abnormal gastrointestinal motility and visceral hypersensitivity may be possible major pathophysiology of irritable bowel syndrome (IBS). These factors affect each other and are probably associated with development of IBS symptoms. It has been confirmed that lower pain threshold to colonic distention was observed in most of patients with IBS than healthy subjects. We have investigated pain perception of the descending colon among different subtypes of IBS. There was no difference in pain threshold to colonic distention between IBS with diarrhea and constipation. Some brain regions such as the anterior cingulate cortex (ACC) may play a major role for generating pain and/or pain-related emotion in humans. IBS patients showed greater activation in the perigenual ACC during painful rectal distention compared with healthy subjects. Inflammation, stress and the combination of both stimuli can induce significant increase in visceral sensitivity in animal models. Serotonin (5-HT) can modulate visceral perception. It has been thought that 5-HT(3) receptors may play an important role for conveying visceral sensation from the gut. Corticotropin-releasing hormone (CRH) may also modulate visceral pain hypersensitivity in IBS. CRH receptor-1 antagonist significantly prevented an increase in gut sensitivity in rats. It has been demonstrated that non-specific CRH receptor antagonist α-helical CRH significantly reduced abdominal pain score during gut stimulus in patients with IBS. In conclusion, visceral hypersensitivity is common in IBS patients and probably plays a major role in development of the symptoms and both central and peripheral factors may enhance the pain sensitivity.